How we play memories in fast forward decoded

Ever wondered how you can recall a recent event in a fraction of the time it took you to live it? Scientists may have the answer!
Researchers have discovered a mechanism that may explain how the brain remembers nearly all of what happened on a recent afternoon - or make a thorough plan for how to spend an upcoming afternoon - in a fraction of the time it takes to live out the experience.
The new mechanism compresses information needed for memory retrieval, imagination or planning and encodes it on a brain wave frequency that is separate from the one used for recording real-time experiences.

Brain cells share different kinds of information with one another using a variety of different brain waves, analogous to the way radio stations broadcast on different frequencies.
Researchers found that one of these frequencies allows us to play back memories - or envision future activities - in fast forward.
"You can plan out those events and think about the sequences of actions you will do. And all of that happens on a faster time scale when you are imagining it than when you actually go and do those things," said Laura Colgin from the University of Texas in Austin, US.

In the brain, fast gamma rhythms encode memories about things that are happening right now; these waves come rapidly one after another as the brain processes high-resolution information in real time.

The researchers learned that slow gamma rhythms - used to retrieve memories of the past, as well as imagine and plan for the future - store more information on their longer waves, contributing to the fast-forward effect as the mind processes many data points with each wave.
Mental compression is similar to what happens in a computer when you a file is compressed. Just like digital compression, when a person replays a mental memory or imagines an upcoming sequence of events, those thoughts will have less of the rich detail found in the source material.

The finding has implications for medicine as well as for criminal justice and other areas where memory reliability can be at issue, researchers said.
The breakthrough in understanding a previously unknown function in the brain has implications for research into schizophrenia, autism spectrum disorders, Alzheimer's disease and other disorders where real experiences and ones that exist only in the mind can become distorted, they said.
"Maybe people with schizophrenia are transmitting their own imagined thoughts on the wrong frequency, the one usually reserved for things that are really happening. That could have terrible consequences," said Colgin.
The findings were published in the journal Neuron.